Recap of Water Year 2008 Hydrologic Forecast and Forecasts for Water Year 2009 Francisco Munoz-Arriola Alan F. Hamlet Shraddhanand Shukla Dennis P. Lettenmaier JISAO/CSES Climate Impacts Group Dept. of Civil and Environmental Engineering University of Washington

Recap of WY 2008

ECMRWF ENSO anomaly 2008 European Centre for Medium-Range Weather Forecasts

Validation Plot for 2008 Forecast (All Cool ENSO composite) Modified Flow (cfs) The Dalles

April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies.

Natural Flows at Milner

Natural Flow (KAF) Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations Simulated Natural Flow at Milner (ESP all years) Milner

Natural Flow (KAF) Red = long term mean Blue = ensemble mean Gray = ensemble members Black = range of observations Simulated Natural Flow at Milner (ESP cool ENSO) Milner

WY 2008 Forecast

WY 2007WY 2008 Potential Implications of ENSO Transition States WY 2009

al_range_forecast/nino_plumes_public_s3/ European Centre for Medium-Range Weather Forecasts ECMRWF ENSO anomaly

April-September Naturalized Flow for the Columbia River at The Dalles, OR from Historic Water Years vs January Nino 3.4 Anomalies.

Natural Flows at Milner

West-Wide Hydrologic Forecast

UW Forecast Approach Schematic NCDC COOP station obs. up to 3 months from current local scale (1/8 degree) weather inputs soil moisture snowpack VIC Hydrologic model spin up SNOTEL Update streamflow, soil moisture, snow water equivalent, runoff 25 th Day, Month years back index stn. real-time met. forcings for spin-up gap Hydrologic forecast simulation Month 12 INITIAL STATE Observed SWE Assimilation ensemble forecasts ESP traces CPC-based outlook NCEP CFS ensemble NSIPP-1 ensemble West-wide System

Ensemble Streamflow Prediction (ESP) ICsSpin-upForecast observed recent met data to generate “perfect” ICs ensemble of historical met data to generate ensemble forecast hydrologic state Applications: climate forecast

Soil Moisture and Snow Water Anomalies

SWE and SM Simulated Climatological March April February

SWE and SM Simulated Climatological MarchFebruaryApril JulyAugustSeptember

Based on Milner Climatology All Years Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes

Based on Dalles Climatology All Years Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes

Based on Milner Climatology ENSO-Neutral Years Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes

Based on Dalles Climatology ENSO-Neutral Years Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes

3.4 Range to 0.2 Based on Milner Climatology Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes

3.4 Range to 0.2 Based on Dalles Climatology Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes

West-Wide Hydrologic Forecast

West Wide Forecast ( ) All Years Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) Milner

West Wide Forecast ( ) All Years Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) Dalles

ENSO-Neutral Years West Wide Forecast ( ) Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) Milner

ENSO-Neutral Years West Wide Forecast ( ) Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) Dalles

3.4 Range to 0.2 West Wide Forecast ( ) Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) Milner

3.4 Range to 0.2 West Wide Forecast ( ) Ensemble Mean Climatological Mean Ensemble Members Climatological Extremes ENSO-years Mean (N) Dalles

UW Forecast System in the Snake River Hells Canyon Dam Milner

UW Forecast System in the Hydropower-related stations at the Columbia River Grand Coulee Chief Joseph Dam

Conclusions: Cool ENSO event during the winter of , increased above average Apr-Sep flow at Milner High snowpack during winter-spring was associated with low values in soil moisture The WY 2008 ESP forecast predicted increased likelihood of wet conditions. Observed summer flows at Milner in 2007 were above average (~25% of normal for April-Sept) Current soil moisture conditions may contribute to slightly reduce streamflow generation during the Jan-June period by 3%. The west-wide forecast system predicts flows similar to those observed in the climatologies for the Dalles, However for the Milner stations there is a increased likelihood of drought and consequently flows slight below normal for the coming water year. Slightly below climatological values Slightly above -0.6-to-0.2 ENSO neutral values On the average of ENSO neutral years

WY 2007WY 2008 Potential Implications of ENSO Transition States

Historic Dalles Apr-Sept streamflow anomalies for water years with previous winter warm ENSO, current winter cool ENSO Stats: 12 of 13 above of 13 above of 13 above 0.88 WYStd Ann.

Natural Streamflow (cfs) Based on Dalles Climatology

Historic Milner Apr-Sept streamflow anomalies for water years with previous winter warm ENSO, current winter cool ENSO WYStd Ann. Stats: 5 of 7 above of 7 above 1.7

enso_2008enso_trans_2008 Based on Milner ESP Natural Flow (KAF)